I would be hesitant because you are a green rider trying to train a horse more than anything. Because at some point in time you will most likely need someone's assistance in training this horse, and that is never cheap. Honestly, it doesn't matter how much time you have on your hands if you don't know what you are doing when it comes to breaking horses. Horse knowledge can't all be found by reading books and articles. I'm not trying to sound rude as I do believe it is do able for an experienced horse person to own a horse on a budget, but the way you are describing the situation you aren't that experienced rider.
I mostly agree with this. There was one point in my riding/ownership career in which I was dead broke and that was when I bought a horse too inexperienced for me. The cost of training and
lessons doubled from that of an experienced, more seasoned horse.
I ended up getting so far in debt due to an additional $600/month being tacked onto my regular horse expenses for training ALONE. A few times I had to ask my friends and family for money to pay my rent bill, AND we had two incomes in our house!
That was absolutely unacceptable.
So I made the executive decision to sell my horse and get a more experienced horse who had some show experience. She is well trained, and of course had some things that needed to be worked on, but now I only pay for lessons -- where I learn to ride and train my horse. I've only had to have one training ride put on her ($25 cost per ride at my barn). The rest my instructor and I work on during my lessons, which I would be paying for anyway. Plus most places offer a discount if you take lessons on your own horse.
I had to take my horse to the vet today which cost me $225 - something that I would no way have been able to afford a few months back in the situation described above. This time I had already half of that cost saved up (I put small amounts away every paycheck as a rainy day fund now for these types of things). I was able to afford this comfortably.
Would I be able to afford an emergency colic surgery? No, and most couldn't without making payments. But I CAN afford the basic once-in-a-while vet visit which is so important. You need to be able to afford the reasonable
So my answer to your original questions is, yes, you absolutely can afford horses on a budget. I guarantee you 90% of horse owners are on some kind of budget. They have houses and vehicles and bills to pay for outside of their horse ownership. Not a very large amount of our population is so rich they don't need to worry about money.
My suggestion is not to adopt this horse. If you are interested in ownership, take the time to invest in a horse who will invest in you. Take some one with much more experience than you and try some out, and get a horse that suits your needs and will take care of you. If you can't afford the initial cost of a horse, and could only own by adopting, I highly suggest not buying at this time.